Understanding Jus Cogens and Treaty Amendments in International Law

Posted on Mar 4, 2025 in Law

Binding Rules on States

These rules are binding on all states, as defined in Article 53 of the Vienna Convention of 1969. They are standards that meet the following requirements: being accepted and recognized, with no derogation permitted. They may only be modified by a subsequent norm.

Consequences Established by the Convention

As a result, the Convention itself establishes consequences: any treaty that conflicts with a norm of jus cogens is void. If a new rule of jus cogens conflicts with a prior treaty, that treaty becomes void and terminates.

Identification of Jus Cogens Norms

The main problem is that there is a list of rules of jus cogens. Certain international organizations (IO) have spoken about it. The International Court of Justice (ICJ) in the Barcelona Traction case declared the prohibition of aggression and genocide as norms of jus cogens. The Human Rights Committee expressly declared that the prohibition of torture is also a norm of jus cogens. Along with these statements, scientific doctrine has argued that the obligation of peaceful settlement also possesses this character.

Treaty Amendment Procedures

Treaty amendment is an alteration of the text of the agreement between the parties. Multilateral treaties may be amended by the same procedure, and if that fails, anyone wishing to amend the treaty must notify the proposed amendment to all contracting states. These states may accept, oppose, or participate in negotiations regarding the amendment.

Effects of Amendments

The effects of the amendments govern inter partes between states that have not expressed their consent to be bound by the amendment and the original treaty. Therefore, possible situations are:

  • States of the original agreement that have not expressed their consent to be bound by the new agreement shall be governed in their mutual relations by the original agreement.
  • The original states that have consented to be bound are governed by the amended agreement.
  • Those who have not consented are governed by the original agreement.
  • New states party to the agreement after the amendment enters into force shall be governed by the amended agreement.

The possibility exists that an amendment takes effect erga omnes for all states ratified by two-thirds.

Invalidity of Treaties

The Vienna Convention mentions a comprehensive set of grounds for invalidity, which are:

  • Violation of a rule of fundamental importance to the law.
  • Failure to comply with specific restrictions of state representatives, provided it has been notified to the other states regarding their powers of expressing consent.
  • Error about a situation that is the essential basis for providing consent, provided that the state does not contribute to creating the error.
  • Corruption of a state representative by another state.
  • Consent to be bound obtained by coercion of the state representative through acts or threats.
  • Celebration of the treaty obtained by threats or use of force.
  • Contrary to a norm of jus cogens.

Termination of Treaties

Causes for termination include:

  • The consent of the parties referred to in a subsequent treaty or agreement, express or implied.
  • Violation or complaint by a party. If the complaint is not covered by the treaty, it is allowed if it appears the intent of the parties to authorize it or is derived from the nature of the treaty.
  • In case of silence, who wishes to withdraw from a treaty must give 12 months’ notice.
  • For serious violations of the treaty.
  • By subsequent impossibility of compliance.
  • For fundamental change in the circumstances prevailing at the time of conclusion of the treaty not intended by the parties, provided that:
    • The circumstances beyond the essential basis of consent.
    • The treaty does not establish a border.
    • There is no violation by invoking it.
  • By the appearance of a standard of jus cogens.

The Vienna Convention states that the following are not grounds for termination: reducing the number of parties to a number less than necessary and the rupture of diplomatic relations.